Columns on sustainable and profitable growing with Plant Empowerment

Short columns on various aspects of sustainable and profitable growing with Plant Empowerment by the Authors and guest writers. Sometimes with surprising insights and out-of-the-box ideas.
Be aware that these columns may contain bold statements putting question marks on prevailing methods and opinions.

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The seven certainties of Plant Empowerment

By J.O. Voogt  March 2024

Everyone has helped a child get started on a swing. You need to give the right push at the right time, not too softly, but not too wildly, so that the swing has a nice cadence and the child has a good time. But how do you know for sure what the right push is at the right time?

In a certain way, the swing is a metaphor for traditional cultivation methods. The aim is to bring and maintain the growth and development of the crop in the right balance by constantly observing the current state of the crop and pushing it in the right direction with generative and vegetative actions. Some growers and advisors are so familiar with this that they do not dare to venture into Plant Empowerment methods and prefer to hold on to their old (un)certainties. When I tell them about the benefits of Plant Empowerment, I receive responses such as: “You may be right, but I cannot afford to take any risks; I prefer to be on the safe side.”
That is why it may be good to take a closer look at the seven certainties of Plant Empowerment.

Certainty 1: You will instantly be a front-runner in sustainability

Plants are naturally highly sustainable and efficient. The Plant Empowerment principles allow you to make optimal use of this, resulting in efficient use of light, CO2, water, nutrients and energy. A healthy, strong crop is also resistant to diseases and pests. That makes cultivation innovation with Plant Empowerment the first and most crucial step in the sustainability transition. As a result, sustainability, resilience and good cultivation yields go hand in hand.

Certainty 2: You know exactly what you are doing

Plant Empowerment is based on physiological and physical laws and works with plant and greenhouse balances. If you monitor and support these balances, the growth and development of the crop becomes predictable. It’s just like a swing. After all, it works according to the principles of the pendulum. This allows you to determine precisely when to give the next push. If the climate control in the greenhouse is programmed and set according to physiological and physical laws, you do not have to monitor how the crop responds constantly. You already know that in advance. That gives you peace of mind and time to think about other things.

Certainty 3: You will go straight to your goal

With Plant Empowerment, you follow a targeted and well-thought-out strategy recorded in the cultivation plan. You monitor the cultivation progress with objective data from sensors and observations and test this against the cultivation plan. In the event of deviations, you do not discuss or speculate, but you trace the real cause through a structured approach from main points to details. This way, you go straight to your goal. This provides guidance and ensures well-founded decisions.

Certainty 4: Your crop is always in top condition

By supporting the plant and greenhouse balances and not disrupting them, you prevent imbalances, both in the long and short term. By applying, among other things, a stable temperature/light ratio (RTR) and by managing the plant load, the plant itself finds the right balance between generative and vegetative development. The plant remains healthy and robust, develops regularly, does not get stressed, and can always do what it does best: grow and bloom. This results in sound production and quality.

Certainty 5: You never lag behind the facts

Because the cultivation process is controlled according to the laws of plant physiology and physics, you know in advance what to do if, for example, the weather changes. We call this proactive or anticipatory management. You take the necessary measures on time, and you will not be faced with unpleasant surprises. It is not without reason that the proverb says: “Prevention is better than cure”.

Certainty 6: You learn quickly

With Plant Empowerment, you work based on reliable data, such as sensor measurements and objective crop observations. Of course, you need the necessary knowledge, insight, and some experience. But that is much faster than with traditional cultivation methods. You can easily exchange data and knowledge with other growers and advisors when working according to the Digital Growing method with Plant Empowerment and the uniform monitoring protocol. This quickly makes you an expert and valued grower or advisor.

Certainty 7: You innovate faster and more efficiently

Because you know what the plant needs for good growth and development, you can also determine where the greenhouse, installations, etc., can be further improved. After all, technology is not a goal in itself but only a means. This gives direction and priority to the innovation process and protects you from unprofitable investments in expensive installations you do not need. Moreover, you do not have to learn to grow again and again. That saves a lot of time and money.

Do you dare to take a first step towards more certainty?
The above list is certainly not complete, but the conclusion is clear that, on balance, Plant Empowerment offers much more certainty than traditional methods. More than 15 years of experience in research and practice have proven this. The much faster learning curve is also excellent news for novice growers.
Do you dare to take the first step towards greater cultivation security and returns? You could do this by studying the books on Plant Empowerment, the basic principles, and Digital Growing. For more information and to order the books, go to the books section.
Like many other growers, you will discover that growing can be very different, more straightforward and even better. Your plants will certainly reward you for it.

By J.O. Voogt,
Copyrights: PlantPhysiLogics Consultancy.

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Digital and Autonomous Growing with AI or PI?

By J.O. Voogt  February 2024

In the past, the common idea in horticulture was that successfully growing vegetables and flowers was mainly a matter of green fingers and experience. And, of course, also a touch of entrepreneurship. That old idea seems to have been turned upside down in recent years. It is now Intelligent Computer Algorithms, Artificial Intelligence, Enforced Learning, and Digital Twins that are setting the tone.
The developers of these new techniques seem to want to convince us that this will greatly improve cultivation results in the long term. We just have to be patient because it is not ready for daily use yet…

But do the AI trees really reach the sky? And how long do we have to wait for it? And what is the alternative? What can we do today with PI to grow sustainably and profitably?

Can AI live up to the high expectations?

Artificial Intelligence (AI) is undeniably a fantastic and powerful tool to help solve very complex issues. Where the human brain can only consider a handful of factors at a time, smart computer programs can quickly and efficiently find the way out of a maze of data. At first glance, it seems logical to optimise plant cultivation with the help of AI. The AI programs are fed with historical climate and cultivation data. From this, the software can derive the relevant cause-and-effect relationships. Together, these relationships form a digital model of the cultivation or crop, also called a “Digital Twin”. Based on current data, these models can then (help) control the cultivation by indicating which measures will give the best cultivation results.

Yet Digital Growing with AI proves to be much more difficult in practice than often thought for at least two fundamental reasons.
Firstly, the quality of historical climate and cultivation data from current greenhouse horticulture, both in research and practice, is extremely questionable. In most cases, the data is incomplete, inaccurate and lacks standardised measurement protocols.
Secondly, current cultivation methods are mainly based on green fingers, feeling and experience, aimed at instantaneously correcting subjectively observed deviations. Therefore, the route that led to a certain result cannot be clearly reconstructed afterwards.

Consequently, it is very optimistic to expect that an analysis of this historical cultivation data would lead to optimal cultivation management. Even the smartest computer with AI cannot turn incomplete and inconsistent data into valuable information. “Garbage in = garbage out.” This does not mean that AI cannot make a useful contribution in the long term. But this first requires several other steps.

The faster route with Plant Intelligence (PI)

Fortunately, there is a much faster route by using Plant Intelligence. After all, plants have been growing completely autonomously for millions of years. PI enables a plant to grow under highly variable conditions and to keep its three balances for energy, water and assimilates in equilibrium. The balances form the primary conditions for life for the plant. The plant can grow and flourish as long as these balances are in order. However, if one of these balances is disturbed, the plant must take measures to restore the balance, which is logically at the expense of growth and development.
This insight forms the basis of the innovative cultivation method of Plant Empowerment. This method aims to monitor and support the plant balances in combination with the greenhouse balances. The plant remains in balance and, with the help of its built-in PI, can do what it does best: grow and bloom according to the laws of plant physiology and physics. As a result, plant behaviour becomes not only predictable but also manageable.
More than 15 years of research and practice have shown that this cultivation method is sustainable and profitable.

Digital Growing with Plant Empowerment

The new book “Plant Empowerment Digital Growing” describes how digital techniques can effectively contribute to optimal crop cultivation results. The laws of plant physiology and physics form a solid and clear framework. We support the plant’s growth process by applying Plant Empowerment principles and clearly distinguishing between long and short-term growth factors. This can make optimal use of its built-in PI for growth and flowering. The result is a strong, healthy, resilient crop with high production and quality. With the bonus of efficient use of energy, water, CO2 and nutrients.
And that is good news because then we do not have to wait for the further development of AI for sustainable and profitable cultivation. We can start today with PI and Plant Empowerment.
For more information and to order the book, go to the books section.

By J.O. Voogt,
Copyrights: PlantPhysiLogics Consultancy.

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Why do we have to learn how to grow crops again and again?

By J.O. Voogt  February 2022

As a teacher in the Dutch training program for growers, Het Nieuwe Telen (HNT), I occasionally hear from my students the remark, or rather the lament: ‘As growers, we have to learn how to grow our crops again and again…’ And let’s be honest, these are challenging times for most growers. And on top of that, we have to make the transition to more sustainability and less CO2 emissions. At the same time, we have to deal with ever-tighter regulations in the field of crop protection, not to mention the skyrocketing gas prices. Please, give us a break!

Innovation of technology
The old-fashioned idea that you learn everything at school for the rest of your life has now been abandoned throughout society. Due to technical innovations, everything is changing so quickly that we have switched to continuous education. You have to keep on learning to keep up with everything. If you don’t, you will be passed and left behind. This is especially true in greenhouse horticulture, where innovation seems to be going even faster than in the rest of the world. The one new technique has barely been put into practice, or the next is already tumbling over it. We innovate our socks off. And as a result, as growers, we have to learn how to grow our crops over and over again.
This was the case, for example, when we (forced) switched to substrate cultivation. But thanks to a huge effort from practice, research, and suppliers, we managed to develop a new cultivation method that enables an even higher production per m2.

Innovation of lighting
This was also the case with the introduction of energy screens, during the energy crisis in the 1970s and later with the application of intensive lighting with HPS lamps and the emergence of diffuse glass. Through trial and error, we also mastered those techniques.
The introduction of the semi-closed greenhouse at the beginning of this century was a real challenge. This did not simply require learning how to grow again but was even labelled as a quest in three dimensions. And more recently, with the large-scale application of LEDs, the cry is once again sounding: ‘We have to learn how to grow again’. And we are not ready yet, because soon we can’t use natural gas anymore and CO2 dosing will become much more expensive. So there is still a lot to learn.

Innovation of cultivation methods
Learning how to grow again and again costs us a lot of time, energy, and money. Then one sometimes thinks: could this be done differently? And yes, I think so. The problem is that we always start from technical innovations and that we have to integrate these into our cultivation methods. That means that we first try to find out how our plants respond to these new techniques and then experiment and adapt until we get a good result again. That is a difficult path.
Suppose we turn it the other way round completely? If we knew what a plant needs to grow and produce sustainably and efficiently, we were able to design a proper cultivation method. And then we can figure out which technical installations are required for this. Wouldn’t that make the puzzle a lot easier? Because plants don’t innovate so quickly. They have grown in almost the same way for millions of years.
In short, let’s just stop being guided by technical innovation, but first, innovate our cultivation methods wherein the plant takes the centre stage. Then we can continue to improve all that technology, but we don’t have to learn how to grow anymore. Technological innovation should be considered as a tool, rather than a goal.

Empower your plants
However, you may ask: what do you mean by focussing on the plant rather than on technology? Besides, aren’t we already doing that? And how can we measure and assess whether we are doing the right things for the plant indeed?
Well, we happen to know something about that. At least we know the basic principles. And if you apply these consistently, you’re already well on your way. How does that work? You can learn that by attending a Plant Empowerment course. And then you have to put it into practice and empower your plants. The good news is that your plants don’t have to get used to that, they will love it and reward you for it.

< This column has also been published on Kas Als Energiebron >

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Why do plants have trouble with LED lighting?

By J.O. Voogt  december 2021

As a teacher of the education program on sustainable growing in the Netherlands (HNT), I regularly receive questions about LED lights. Such as: what is the effect on plant growth and how best to integrate LEDs into climate control? Ever since the introduction of LED lighting, it has been noted that plants show different reactions than under sunlight or under the common HPS lamps.

This is not surprising in itself, because plants usually grow under natural sunlight, which has very different properties than artificial light.
When people started growing plants under low-pressure sodium lamps, or street lamps, this was already apparent. The solution then was to switch to high-pressure sodium (HPS), the spectrum of which contains more blue. Apparently, a plant needs that for natural development. For the same reason, about 5% blue is now mixed with red LED light as standard, creating the characteristic purple LED light.

LED spectrum offers new possibilities
In recent years, much research has been done into the effects of the spectral composition of LED light. The idea is that specific light colours can promote certain desired developments and inhibit others. An example is that Far-Red light leads to more stretching, which is favourable for good light distribution in the crop, among other things. More blue (UV) light gives a more compact growth. Experiments are also underway with green and white LED lights. And undoubtedly there is still much interesting to discover.

LED grow light costs less electricity
The main reason for using LEDs on a large scale is now the fact that they generate PAR light very efficiently. LED produces more PAR and therefore potentially more kilos of fruit or more flower sprays and pot plants per m2 at the same electricity costs. LED also allows higher light levels under a blackout screen closed against light emission without the temperature rising too much. Where previously a level of 200 micromols/m2.s PAR with HPS was common, 300 micromols is now starting to become the new standard in some crops. Theoretically, that could yield 50% more production.
In short, LED seems to be the ideal light source for the sustainable greenhouse horticulture of the future. Provided that there is enough green energy available.

How do plants feel under LED light?
Unfortunately, it is becoming increasingly clear that issues can also arise under intensive LED lighting. To name a few: purple discolouration of leaves and flowers, bumpy leaves and shorter vase life. It is also found that photosynthesis does not increase proportionally with higher PAR levels, but is inhibited by anthocyanin formation. The suspected causes are the light spectrum, but also the hormone balance of the plant, temperature effects and possible nutrient deficiencies. The last two factors make it interesting to look at the physical properties of light sources and how they affect the plant, in terms of temperature and evaporation.

How does LED affect nutrient uptake and crop temperature?
Light sources are characterized by their spectral composition. PAR light (400 – 700 nm) determines photosynthesis potential. The other components, with shorter or longer wavelengths in the radiation, contain energy that can heat up plant parts and drive evaporation. In addition, artificial light sources (fixtures) produce convection heat that can contribute to this through air movement.
At the same PAR intensity (micromol/m2.s), LED delivers roughly less than half the energy to the crop compared to sunlight and HPS light. That also means half the evaporation and nutrient supply. And of course also less heating of the head of the plant, leaves, buds, fruits, etc. And that warming up is actually beneficial to accelerate the process of photosynthesis and to keep the transport and consumption of the sugars formed in balance with the production.
Over millions of years, plants have adapted to the spectral composition of sunlight. If those plants receive mainly or even exclusively LED light, the normal relationship between assimilates production and nutrient availability is therefore out of balance. And due to the lower plant temperature, the source and sink activity will also be less.

How can LED really become a success?
So, LED light is very efficient when it comes to PAR light, but at the same time, it significantly disturbs the natural plant balances in terms of energy, water, assimilates and nutrient uptake. Additional measures need to be taken to get those balances back in order. For example, in cultivation cells and multi-layer cultivation (vertical farming), intensive air circulation is usually provided to obtain an even temperature and moisture distribution, both horizontally and vertically. This also gives a considerable increase in evaporation and thus in nutrient uptake.
How this should be done in normal greenhouses is not yet entirely clear. Maybe, choose the heating temperature setpoint higher than normal, or install an (extra) growth tube at the head of the crop or at the flower buds? Perhaps a different composition of the nutrient solution, or perhaps more (vertical) air movement? Or is hybrid lighting not a bad idea after all? Screens against radiation to prevent the crop from cooling down are an obvious choice in any case.
In any case, one thing is clear; to make the large-scale application of LED a real success, we will have to take the natural needs and properties of plants more into account and not just focus on technology. In addition to light utilization, heat utilization is also essential in the context of sustainability.

Faster and more efficient
Fortunately, we now have modern sensors such as the net radiation meter and the thermographic camera. This allows the energy input to the plant and the (vertical) temperature distribution to be measured and visualised directly. This, therefore, works much faster and more efficiently than the old-fashioned research method of trial & error.

* This column has also been published on Kas Als Energiebron *

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Who still believes in the pre-night drop and morning dip?

Introduced about two and a half decades ago, the idea of using a sharp temperature drop to encourage fruit production is still a source of contention.

November 2020  By Jan Voogt

As a teacher of the “HNT (Het Nieuwe Telen) Learning Groups”, an educational program where Dutch growers are taught the principles of Next Generation Growing / Plant Empowerment, I am frequently asked whether I am in favour of the pre-night drop (PND) and morning dip (MD).

As I recall, the idea of the pre-night drop in tomato cultivation popped up in The Netherlands about 25 years ago. At the end of the afternoon, the temperature in the greenhouse had to be lowered considerably in one rapid motion – the faster the drop in temperature, the better. This was believed to push the assimilates towards warmer fruits, so they become bigger. Besides, it was assumed to promote strong plant heads and trusses.

However, there have been questions from the beginning as to whether this hypothesis is correct. I still remember how one renowned crop adviser argued, that after a sunny day, you should allow the plant to process the assimilates produced during the day; however, the pre-night drop would make this more difficult. This adviser published yield figures of growers who used the pre-night drop and those who didn’t apply it. Although there was no noticeable effect of PND, it did not help to support his case. It was like crying in a desert.

More recently, the idea of the so-called morning dip arose, which is also very commonly applied. After a night under a closed or non-closed energy screen, you should theoretically let the greenhouse temperature make a short dip. This is supposed to promote strong, short trusses. Both the PND and the MD are widely considered generative actions and form the basic tools of any serious tomato grower and crop consultant. There have been no discussions about this for a long time.

Considering Plant Empowerment
We have been reconsidering both hypotheses in light of the principles of Plant Empowerment. Again, considerable doubts arose. Warmer parts of the plant can attract more assimilates, but colder leaves also release the formed assimilates more slowly. So, with quick cooling during the pre-night period, wouldn’t you shoot yourself in the foot? Moreover, this stagnates the supply of nutrients, including calcium, to the growth point. Wouldn’t this increase the risks of, for instance, blossom end-rot and tip-burn? A rapid build-up of root pressure can also cause guttation. And after preparing the crop for the day with a slow warm-up, what does a morning dip do to the activity of the plant? Which runner would take a cold shower after his warm-up exercises, just before starting the race?

Data from WUR research
In response to these doubts and questions, Wageningen University & Research (WUR) conducted an extensive study into the effects of temperature treatments on greenhouse crops. The results were published in a 2012 report called ‘Temperature strategies in conditioned greenhouses, Effects on growth, development and underlying processes in tomato’ (Report GTB-1123, available in Dutch on the website In short, all three hypotheses considered to be the basis for PND and MD have been proven incorrect in this study:

  • A pre-night drop does not increase the transport of assimilates to the fruits and does not increase fruit weight;
  • Plant cell elongation cannot be influenced by a temperature strategy such as PND and MD;
  • Most cell elongation does not occur in the morning but in the evening.

These findings coincide with the principles of Plant Empowerment, which advocate for, among other things, keeping the screen closed for longer at the start of the day and closing the screen earlier (to 80%) at the end of the day. This helps protect the plants against the negative effects of heat emission by longwave radiation. This screening method also ensures better moisture control and the effective use of free energy from the sun.

New experiences
These new insights on PND and MD have been slowly implemented in practice throughout the last ten years. Fortunately, there are now sensors which provide increasing evidence to support this with hard facts. Total plant weight measurements demonstrate that a PND slows down growth substantially. Thermographic images show that MD can lead to more water stress when the sun’s radiation intensifies. More and more growers tell me that they have gradually abandoned their familiar PND and MD strategies only to see positive results occur, including healthy growth at the plant heads, good fruit set, and strong trusses. In the meantime, they have learned that the desired crop development (generative/vegetative) can be achieved more easily by maintaining a steady ratio between the 24-hour temperature and the light sum daily and by controlling the plant load. This stabilises the assimilates balance and affects almost all plant processes, including the plant’s health in a positive way.

Believers and non-believers
What concerns me now is that these growers sometimes tell me confidently that they hardly dare to share this information with their colleagues. They seem to think that if your opinion differs from the rest of the group or if you question the advice of a well-known crop specialist, you will be considered a non-believer or shunned, and you will no longer be taken seriously. That feels very uncomfortable, and not uncommonly, growers will return to the old methods under this peer pressure. One would think that PND and MD are a part of some belief system. Everyone can have their own opinions, which is always food for thought and good for discussion. But if you are no longer open to new facts and insights, then development stagnates. And, as Dutch growers often say, “Standing still is moving backwards.”

Autonomous Greenhouse Challenge 2020 – Tomatoes
Recently, the world learned how the “Automatoes” team won the Autonomous Greenhouse Challenge organised by WUR this past spring. Surprisingly, this was achieved without the use of PND or MD whatsoever. The winning team claims to have applied smart computer algorithms, also known as Digital Growing, in addition to the principles of Plant Empowerment. They maintained a steady temperature/light ratio and consistently protected the crop against heat emission during the cultivation period. This way, they made optimal use of the plant’s natural growing power, leading to the highest yield, the best quality, and growing the most efficiently and sustainably of all competing teams.

Working together sustainably
Hopefully, this article will prompt believers to reconsider the supposed benefits of PND and MD. I also hope this may encourage non-believers to come forward with their experiences. Because efficient, sustainable, and profitable cultivation is the real challenge to which the entire horticultural sector faces, we must all work in unison to test new insights critically and to also dare let go of old, outdated insights. Intelligent computer algorithms can help us because they do not work based on feelings and habits, only on hard facts. Digital Growing has no difficulty switching to new strategies if they yield better. The outcome of the Autonomous Greenhouse Challenge indicates how the transition to sustainable and profitable greenhouse horticulture can be accelerated.

* This column has also been published on Greenhouse Canada and Kas Als Energiebron *

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The book

“Plant Empowerment the basic principles”